Magnet system for converting electric oscillations into acoustic ones or conversely



Sept. 6, 1932. 1,876,113

R. VERMEULEN 1 MAGNET SYSTEM FOR CONVERTING ELECTRIC OSCILLATIONS INTO ACOUSTIC ONES OR CONVERSELY Fil'd Aug. 10, 1928 INVENTOR ROE F VERMEULEN BY %4 Jada 'A ORNEY BOELOF VEEMEULEN, OF EINDHOVEN, NETHERLANDS, ASSIGNOB, TO .TION OF AMERICA, A CORPORATION OF DELAWARE MAGNET SYSTEM FOR CONVERTING ELECTRIC OSCILLATIONS INTO ACOUSTIC ONES OR Patented Sept. 6, 1932 V UNITED STATES PATENT; OFFICE;

mm com-o a- CONVERSELY Application filed August 10, 1928, Serial No. 298,827, and in the Netherlands September 24, 1927.

This invention relates to a magnet system for converting electric oscillations into acoustic oscillations and conversely. More particularly it relates to a magnet system provided with a ferromagnetic armature which is normally balanced in a permanent magnetic field and which is adapted to move from that-balanced position when speech modulated currents are passed thru windings associated with said system.

The invention has for its object to provide a magnet system of the kind referred to which has a very simple construction and which can be cheaply and easily made. Another object is to provide a path of minimum resistance for the alternating flux developed manent magnet through the armature to polesurfaces of a U- or V-shaped pole piece at-- by the speech modulated currents.

The magnet system according to the invention isso constructed that the permanent flux is branched off from one pole, of a pertached to the other pole of the permanent magnet. The active faces of the U shaped pole piece -are normal-to the direction of movement. of the armature, and said pole.

piece constitutes with the armature. a closed circuit for the alternating flux produced by the speech modulated current in flowing thru coils that are mounted on the U-shaped pole v piece. When both the u-shaped pole piece pole piece.

and the armature are laminated, this part will be similar to a transformer core and con seouently will constitute an ideal path for the induced alternating current. The active pole faces of the U-shaped pole piece being normal to the direction of movement of the armature, air gaps will be produced between the ends of the armature and the active faces of the Owing to this arrangement a variation in the magnetic field willex'ercise a greater force on the armature than in the case where the air gap is parallel to the direction of movement of the armature.

In one embodiment of the invention the U- or veshaped pole piece has arranged opposite it another pole piece to, whichthe armature is secured by means of unilaterally clamped springs. The two'pole-pieces may be located essentially in one plane and for convenience can be mounted on a copper plate which is provided with notches adapted to receive the limbs of the magnet. The construction of the magnet system is very simple as it is built up of but four parts. In the first place the horse-shoe magnet which in the majority of cases is permanent but may be provided with direct current windings,- secondly the U shaped pole piece with two coils. that are slipped on the limbs of the U, in the third place the other pole piece to which the armature is secured by means of springs, in the fourth place the copper plate on which the two pole pieces can be mounted by very simple means and which owing to its notches can be very simply slipped on the horse-shoe magnet.

' The invention will be more clearly understood by reference to the accompanying drawing in whichan embodiment of the invention is illustrated. In the said drawing:

Figure 1 is a side view of a magnet system system jress of the permanent and the alternating Before entering into the details ofthe magnet system the principle onwhich it is based will be briefly ex lained with reference to Figure 6. In this igure, 1 designates a permanent magnet. This'horse-shoe magnet has secured to one pole a pole piece 2 and to the other pole a U-shaped pole piece 3. Speech modulated current coils 9 and 10 are mounted on the limbs of the U-shaped pole piece 3.

The ferromagnetic armature 5 is secured to the pole piece-2 by means of springs 12 and 13. Y

the case that the pole piece 2 is secured to t e north pole the permanent fluxwill proceed as indicated by the light line,

through this pole piece to the armature and there be branched off to the two limbs of the U-shaped pole piece 3, the pole faces of which are normal to the direct-ion of movement of the armature. The pole faces are hereinafter understood to mean those parts of the pole piece thattogether with the armature limit the intermediate air gap. As before stated the limbs of the U-shaped pole piece are provided with speech modulated current coils and if the latter are wound in a correct direction an alternating fiux will be produced which makes its way through the armature and the U-shaped pole piece as indicated by dotted lines. From this it follows that this alternating flux traverses a closed circuit constituted by pole piece 3 and armature 5. When these two parts are laminated the resistance for the alternating flux becomes extremely low so that the flux reaches a high value.

In Figure 1 a side view of the magnet system is shown. The U-shaped magnet 1 has mounted on it a copper plate 7 which serves as a mounting plate for pole piece 2 and U- shaped pole piece 3. In Figures 2 and 3 two views of this copper plate with pole pieces mounted on it are shown. As shown in Figure 2 pole piece 3 is secured to the copper plate 7 by means of clamps 8 and that two coils 9 and 10 are mounted on the limbs of the pole piece. Pole piece 2 is fastened to the copper plate 7 by means of screws 11. This pole piece has mounted on its springs 12 and 13 which serve as carriers for the armature 5. A stud 14 which communicates with an oscillation member, for example a cone, is fastened to the armature 5.

Figure 3 shows a bottom view of the copper plate. The notches in which the limbs of the horse-shoe magnet are fitted and by means of which the copper plate 7 can be secured to the limbs of the horse-shoe magnet, are indicated at 15 and 16.

Figures4 and 5 show in detail the pole pieces 3 and2. As shown in Figure 5, armature 5 is secured to the pole piece .2 by means of springs 12 and 13. These springs are unilaterally clamped by means of screws and are secured to the pole'piece 2. Pole piece 3 and armature 5 are laminated so that the alternating flux meets with a low resistance.

Various other modifications can be made' without departing from the spirit of my invention and I do not intend to be limited by the exact structure disclosed but only by the scope of the appended claims.

I claim:

1. In combination a permanent magnet, a U-shaped pole piece fastened to one of the poles of said magnet, an armature positioned with one end adjacent one of the limbs of said U-shaped pole piece and with its other end adjacent the other limb of said U-shaped pole piece, a single limb ole piece'fastened to the other pole of said magnet, said pole piece being positioned with its single limb adjacent the intermediate part of said armature, an operating member connected to said armature, a pair of coils mounted on the limbs of said pole piece, and means supporting said armature for movement along its longitudinal axis.

2. In combination means for forming a permanent field of magnetic flux, a pair of pole pieces for said means, one of 'said pole pieces being branched, an armature positioned between the limbs of the branched pole piece with one end adjacent one limb and the other end adjacent the other limb, a pair of modulated speech current coils mounted on the limbs of said branched pole piece for superposing an alternating field of magnetic flux on said permanent field of magnetic flux, and means for supporting said armature from the other pole piece for movement substantially along its longitudinal axis.

3. In combination a permanent magnet, a U-shaped pole piece fastened to one pole of said permanent magnet, a second pole piece fastened to the other pole of said permanent magnet and positioned to form two air ga between said second pole piece and the lim of said U-shaped pole piece, anarmature sup- 9 ported from said second pole piece and p0- sitioned to move between the limbs of said U-shaped pole piece and a pair of modulated speech current windings mounted on the limbs of said U-shaped pole piece. V

4. In combination a permanent magnet, a U-shaped pole piece fastened to one of the poles of said magnet, an armature positioned with one end adjacent one of the limbs of said U-shaped pole pieceand with its other end adjacent the other limb of said U-shaped pole piece, a driving rod connected tosaid' armature, a pair of supporting springs se cured to the ends of said armature, win surrounding the limbs of said U-shaped po e piece whereby said armature lies within its magnetic field, and a pole piece fastened to the other pole of said magnet and positioned adjacent the side of said armature, said last mentioned pole piece and said armature being arranged so that the air gap between said pole piece and the side of said armature is not varied by vibration of the armature.

5. In combination means for producing a permanent magnetic field, a U-shaped pole piece fastened to said means, a solid pole piece fastened to said means, an armature positioned between the limbs of said U- shaped pole piece and adapted to move substantially along its longitudinal axis, windings surrounding the limbs ofsaid U-sha pole piece, and a pair of springs sec to the ends of said armature and to said solid pole piece.

6. A magnet system for the interconverw a piece and a second pole piece having one sion of electric oscillations and sound waves comprising means including a U-shaped 1pol}? for forming a permanent magnetic field, said U-shaped pole piece being arranged oppo-- site said second pole piece, a ferromagnetic armature arranged in said ma and adapted to move substantial along its longitudinal axis, said armature ein positioned with one end adjacent one of t e pole surfaces of said U-shaped pole piece and with'the other end adjacent the other pole "surface of said U-sha ed pole piece whereby of the magnet.

the permanent flux is ranched ofi'from said second pole piece throu h the armature to v the pole surfaces of said which are normal to the direction of move ment of the armature, said U-shaped pole piece constituting with said armature a closed circuit for alternating flux, coils for the speech modulated current mounted on the U-shaped pole piece to produce said al ternating flux, and springs clamped to said second pole piece and secured to the ends of said armature for supporting said armature.

7. A magnet system according to claim 6, characterized in that the two p0 e pieces are located essentially in one plane and are mounted on a copper plate which is rovided with notches adapted to receive ROELOF VEBJIEULEN.

etic field -shaped pole piece e limbs 

